The present invention relates to intake and exhaust valves for an internal combustion engine.
Known internal combustion engines of either the diesel or the spark ignition type include one or more intake valves which control the flow of an air fuel mixture to a combustion chamber of the engine. One or more exhaust valves are utilized to control the flow of exhaust gases from the combustion chamber of the engine. The power of the engine has previously been limited by the amount of the air which can be drawn into the engine during an intake stroke. If the size of the intake valve is increased, the amount of the air which can be drawn into the combustion chamber is increased. Because exhaust gases are pumped out of the engine by the movement of the piston in the cylinder, the size of the exhaust valve is usually not a limiting factor in the power which can be created by an engine.
In order to increase the amount of the air which is drawn into the engine during an intake stroke, internal combustion engines have been designed with two intake valves for each cylinder chamber. Although the use of two intake valves increases the amount of the air which can be drawn into the combustion chamber, the overall size of the two intake valves is limited by the cylinder head space required for the two intake valve openings and by the cylinder head space required for one or more exhaust valve openings. Of course, the use of two intake valves increases the number of components required in an engine and the cost of the engine.
The present invention relates to a new and improved is combination intake and exhaust valve assembly which is used in an internal combustion engine. The combination intake and exhaust valve assembly includes an intake valve and an exhaust valve which are disposed in a coaxial relationship. A valve seat for a head end portion of the intake valve is disposed on the cylinder head. A valve seat for the exhaust valve is disposed on the intake valve.
When the intake valve is operated from a closed condition to an open condition, the intake and exhaust valves may be moved together. However, the exhaust valve remains in a closed condition. If desired, the exhaust valve could be moved toward the closed condition as the intake valve moves toward the open condition. The intake valve is subsequently moved from the open condition to the closed condition while the exhaust valve remains in a closed condition and moves with the intake valve. If desired, the exhaust valve could be moved toward the open condition as the intake valve moves toward the closed condition.
After an air fuel mixture has been burned in the combustion chamber, the exhaust valve is moved to the open condition. As the exhaust valve begins to move toward the open condition, a head end portion of the exhaust valve moves away from a valve seat disposed on the intake valve. Guides for movement of the exhaust valve relative to the intake valve may be mounted on the intake valve.
The present invention includes a plurality of features which may be used separately or in combination with each other. Combinations of features which are different than the combinations described herein may be used.